This invention refers to an improved apparatus for product-injection into meat pieces. These machines, according to an already known technique, are made up of one or two heads carrying a number of injecting needles and having a periodic, alternative up-and-down movement on a conveyor on which the meat is placed so that the needles stick into it, whereby brine is injected into the meat mass. The injected substance, such as brine, proteins, phosphate or other product, appropriately dissolved, helps in the preservation and/or improvement of the taste and contexture conditions of the treated piece; it is usually supplied at a rated pressure of 5-8 kg/cm.sup.2, which is kept constant even if the flow rate or the percentage of injected substance changes. The injecting needles used are very long, each having defined along its bore and on different sides of its section several orifices of very small diameter. Given such pressure conditions and the small orifices of the injecting needles, a virtual pulverization in the meat area immediate to these needles is caused during the injection phase.
In the Spanish Pat. No. 469,071 granted to the same entity, a description can be found of an injection system which allows one to keep constant the injecting pressure and change the injecting flow rate (speed). Forming a part of the state of the art in this industry is the use of a series of independent pressing blocks, attached to the head by resilient means, through which the injecting needles pass, and which press the meat piece preventing its displacement from the transport plane by adapting themselves to the form of that piece more accurately than a single fixed pressing plate. (Lack of correspondence to the piece outline places different pressures on the different areas of the meat piece, making it difficult to inject liquid thereinto.)